WRAPUP 1-Malaysia plane hunt resumes amidst optimism over "pings"

* Search resumes in refined area

* Sonobuoys to help U.S. Navy vessel search

* Officials optimistic that plane could soon be found

By Matt Siegel and Swati Pandey

SYDNEY/PERTH, Australia April 10 The search for
a missing Malaysia Airlines jetliner resumed on Thursday with a
renewed sense of optimism, after Australian officials said they
had detected two new "ping" signals that may have come from the
plane's black box recorders.

The mystery of Malaysia Airlines Flight MH370,
which disappeared more than a month ago, has sparked the most
expensive search and rescue operation in aviation history, but
concrete information has proven frustratingly illusive.

The announcement on Wednesday that two new "ping" signals
had been detected, bringing to four the number heard by a U.S.
Navy "Towed Pinger Locator"(TPL), led officials to say they were
confident that they were homing in on the remains of the plane.

"I'm now optimistic that we will find the aircraft, or
what's left of the aircraft, in the not too distant future,"
Angus Houston, the head of the Australian agency coordinating
the search, told reporters in Perth.

The black boxes record cockpit data and may provide answers
about what happened to the plane, which was carrying 227
passengers and 12 crew when it vanished on March 8 and flew
thousands of kilometres off its Kuala Lumpur-to-Beijing route.

But the batteries in the beacons have already reached the
end of their 30-day expected life, making efforts to swiftly
locate them on the murky ocean floor all the more critical.

NARROWING THE SEARCH AREA

Up to 10 military aircraft, four civil aircraft and 13 ships
are expected to be involved on Thursday with a massive search
effort that has so far proven fruitless in identifying any
physical evidence of wreckage from the flight.

Efforts are now focused on two areas - a larger one for
aircraft and ships about 2,240 kms (1,392 miles) northwest of
Perth and a smaller area about 600 kms (373 miles) closer to
that city.

Based on data from the four signals detected, a modified
Royal Australian Air Force P-3 Orion surveillance plane is
deploying sonobuoys in the smaller search area to assist the
U.S. Navy listening device that detected the signals.

Each of the 84 sonobuoys is equipped with a listening device
called a hydrophone, which is dangled about 1,000 ft (305
metres) below the surface and is capable of transmitting data to
search aircraft via radio signals.

"That does provide a lot of sensors in the vicinity of the
Ocean Shield without having a ship there to produce the
background noise," said Australian Navy Commodore Peter Leavy,
operational head of the Australian search, referring to the ship
carrying the U.S. listening device.

But experts say that the process of teasing out the signals
from the cacophony of background noise in the sea is a slow and
exhausting process. Operators must separate a ping lasting just
9.3 milliseconds - a tenth of the blink of a human eye - and
repeated every 1.08 seconds from natural ocean sounds, as well
as disturbances from search vessels.

An autonomous underwater vehicle named Bluefin-21 is also
onboard the Ocean Shield, and it could be deployed to look for
wreckage on the sea floor once the final search area has been
positively identified.

As with so many things in this unprecedented search effort,
experts say that will not be an easy task.

"Working near the bottom of the ocean is very challenging
because this is uncharted territory; nobody has been down there
before," Erik van Sebille, an oceanographer at the University of
New South Wales, told Reuters.

Dec 9 Coca-Cola Co said on Friday that
Muhtar Kent would step aside as chief executive next year and be
replaced by James Quincey, a company veteran credited with
several recent changes to help the company cut its dependence on
sugary drinks.

Reuters is the news and media division of Thomson Reuters. Thomson Reuters is the world's largest international multimedia news agency, providing investing news, world news, business news, technology news, headline news, small business news, news alerts, personal finance, stock market, and mutual funds information available on Reuters.com, video, mobile, and interactive television platforms. Learn more about Thomson Reuters products: